From a7213ed931f2504902c3d7378d4423a9984f8635 Mon Sep 17 00:00:00 2001
From: Stefan Kreutz <mail@skreutz.com>
Date: Mon, 19 Dec 2022 18:02:18 +0100
Subject: Add recursive SHA256 example application

---
 examples/.gitignore                   |  2 ++
 examples/Cargo.toml                   |  3 ++
 examples/recursive-sha256/Cargo.toml  | 10 +++++++
 examples/recursive-sha256/src/main.rs | 55 +++++++++++++++++++++++++++++++++++
 4 files changed, 70 insertions(+)
 create mode 100644 examples/.gitignore
 create mode 100644 examples/Cargo.toml
 create mode 100644 examples/recursive-sha256/Cargo.toml
 create mode 100644 examples/recursive-sha256/src/main.rs

(limited to 'examples')

diff --git a/examples/.gitignore b/examples/.gitignore
new file mode 100644
index 0000000..4fffb2f
--- /dev/null
+++ b/examples/.gitignore
@@ -0,0 +1,2 @@
+/target
+/Cargo.lock
diff --git a/examples/Cargo.toml b/examples/Cargo.toml
new file mode 100644
index 0000000..4f10fc3
--- /dev/null
+++ b/examples/Cargo.toml
@@ -0,0 +1,3 @@
+[workspace]
+members = ["*"]
+exclude = ["target"]
diff --git a/examples/recursive-sha256/Cargo.toml b/examples/recursive-sha256/Cargo.toml
new file mode 100644
index 0000000..38ed665
--- /dev/null
+++ b/examples/recursive-sha256/Cargo.toml
@@ -0,0 +1,10 @@
+[package]
+name = "example-recursive-sha256"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+[dependencies]
+parseq = { path = "../.." }
+sha2 = "0.10.6"
+walkdir = "2.3.2"
diff --git a/examples/recursive-sha256/src/main.rs b/examples/recursive-sha256/src/main.rs
new file mode 100644
index 0000000..6fcbbfa
--- /dev/null
+++ b/examples/recursive-sha256/src/main.rs
@@ -0,0 +1,55 @@
+//! Print the SHA256 sum of each regular file in the current directory recursively.
+
+use std::{fs::File, path::PathBuf};
+
+use parseq::ParallelIterator;
+use sha2::{Digest, Sha256};
+use walkdir::WalkDir;
+
+fn main() {
+    WalkDir::new(".")
+        .sort_by_file_name()
+        .into_iter()
+        .filter_map(|entry| match entry {
+            Ok(entry) if entry.file_type().is_file() => Some(Ok(entry.into_path())),
+            Ok(_) => None,
+            Err(err) => Some(Err(Error::WalkdirError(err))),
+        })
+        .map_parallel(|item| {
+            item.and_then(|path| {
+                let mut file =
+                    File::open(&path).map_err(|err| Error::IoError(path.clone(), err))?;
+                let mut hasher = Sha256::new();
+                std::io::copy(&mut file, &mut hasher)
+                    .map_err(|err| Error::IoError(path.clone(), err))?;
+                Ok((path, hasher.finalize()))
+            })
+        })
+        .for_each(|item| match item {
+            Ok((path, hash)) => println!("{:x} {}", hash, path.display()),
+            Err(err) => eprintln!("{err}"),
+        });
+}
+
+#[derive(Debug)]
+enum Error {
+    WalkdirError(walkdir::Error),
+    IoError(PathBuf, std::io::Error),
+}
+
+impl std::error::Error for Error {}
+
+impl std::fmt::Display for Error {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Error::WalkdirError(err) => {
+                if let Some(path) = err.path() {
+                    write!(f, "{}: {}", path.display(), err)
+                } else {
+                    write!(f, "{err}")
+                }
+            }
+            Error::IoError(path, err) => write!(f, "{}: {}", path.display(), err),
+        }
+    }
+}
-- 
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